Google owner Alphabet Inc has made an offer to acquire U.S. wearable device maker Fitbit Inc, as it eyes a slice of the crowded market for fitness trackers and smartwatches, people familiar with the matter said on Monday.

While Google has joined other major technology companies such as Apple Inc and Samsung Electronics Co Ltd in developing smart phones, it has yet to develop any wearable offerings.

There is no certainty that the negotiations between Google and Fitbit will lead to any deal, the sources said, asking not to be identified because the matter is confidential. The exact price that Google has offered for Fitbit could not be learned.

Google and Fitbit declined to comment.

Fitbit shares rose 27% on the news, giving the company a market capitalisation of $1.4 billion. Alphabet shares rose 2% to $1,293.49.

A deal for Fitbit would come as its dominant share of the fitness tracking sector continues to be chipped away by cheaper offerings from companies such as China’s Huawei Technologies Co Ltd and Xiaomi Corp.

Fitbit, which helped pioneer the wearable devices craze, has been partnering with health insurers and has been making tuck-in acquisitions in the healthcare market, as part of efforts to diversify its revenue stream. Analysts have said that much of the company's value may now lie in its health data.

Fitbit cut its 2019 revenue forecast in July, blaming disappointing sales of its newly launched cheapest smartwatch Versa Lite. The watch is priced at $160, compared with $200 for the full version. It can track workouts and heart rate but lacks features such as the ability to store music directly.

In August, Fitbit said it had signed a contract with the Singapore government to provide fitness trackers and services in a health programme it said could reach up to 1 million users.

Fitbit in August also launched its latest smartwatch, Versa 2, adding Amazon.com Inc’s voice assistant Alexa, online payments and music storage to the device’s capabilities.

Fitbit is scheduled to report third-quarter earnings on Nov. 6. Alphabet is scheduled to report third-quarter earnings later on Monday.

Fitbit would not be the first deal that Google would be carrying out in the wearables space. Fossil Group Inc said in January it would sell its intellectual property related to smartwatch technology under development to Google for $40 million. Google's plans for these assets are not clear.

Reuters had reported last month that Fitbit was speaking to investment bank Qatalyst Partners about exploring a sale.